<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    div {
      border: solid;
      width: 400px;
      height: 400px;
    }
    div p {
      border: solid red;
      width: 50%;
      height: 50%;
    }
  </style>
</head>

<body>

  <div>
    <p> this is <span>tag</span> p </p>
  </div>

</body>

</html>